Hole plugs

ABSTRACT

A hole plug for closing a through-hole formed in a compartment wall may include an attaching portion formed from a synthetic resin and a cover portion integrated with the attaching portion at a central portion thereof. The attaching portion can be inserted into the through-hole so as to engage the inner surface of the compartment wall. The cover portion has a size and shape that can enclose the through-hole and has a peripheral edge portion that can closely contact the outer surface of the compartment wall. The cover portion has a thickened portion that is formed in the peripheral edge portion thereof or in a vicinity of the peripheral edge portion and that can maintain a size and configuration of the peripheral edge portion when an external force is applied to the cover portion. The cover portion has a thinned portion that is formed between the thickened portion and the central portion integrated with the attaching portion and that can undergo elastic buckling deformation when an external force is applied thereto.

This is a continuation of International Patent ApplicationPCT/JP2005/009149, filed May 19, 2005, which claims priority of JapanesePatent Application S.N. 2004-153438, filed May 24, 2004.

FIELD OF THE INVENTION

The present invention relates to hole plugs. More specifically, thepresent invention relates to hole plugs for sealing through-holes thatare formed in various portions of a structure of a vehicle such as anautomobile and which through-holes are otherwise left open without beingused.

BACKGROUND OF THE INVENTION

A hole plug of this type is inserted into a through-hole, which isformed in a portion (e.g., a compartment wall) of a vehicle body or thelike at the time of the production thereof and is otherwise left openwithout being used, to thereby seal the through-hole. Therefore, whenthe hole plug is to be applied to a through-hole formed in a portion(e.g., an inner panel) of a door that separates a vehicle interior froma vehicle exterior, the hole plug has to be designed so as to have adesired sealing performance such that rainwater, dust or other suchmaterial is prevented from entering the vehicle interior through thethrough-hole.

The structure of the hole plug will be described hereinafter. The holeplug has a cylindrical attaching portion that is constructed to befitted into a circular through-hole, and a dish-shaped cover portionintegrally formed at a base portion of the attaching portion. In such ahole plug, the attaching portion and the cover portion can be integrallyformed from an elastomer which has a superior elasticity and sealingproperty. Alternately, the attaching portion and the cover portion canbe separately formed and then integrated with each other by bonding. Insuch a case, the attaching portion and the cover portion canrespectively be formed from a synthetic resin and an elastomer. Theseexamples of the hole plug will be briefly described below.

First, in the former type of hole plug, which is integrally formed froman elastomer, a forward end portion of the attaching portion is formedin a truncated umbrella-shape so as to protrude outwardly. Morespecifically, it is formed so as to have a diameter greater than thediameter of the through-hole. Conversely, the cover portion is formed asa truncated reverse umbrella-shape opposite to the umbrella-shape of theattaching portion. Therefore, when the truncated umbrella-shaped forwardend portion of the attaching portion is forced into the through-hole inuse, the portion of the attaching portion is inserted thereinto whilebeing squeezed and narrowed. The forward end portion of the attachingportion is outwardly restored or spread after passing through thethrough-hole, and engages the inner surface of the panel around theperiphery of the through-hole. Also, depending upon the insertingoperation of the attaching portion, the reverse umbrella-shaped coverportion is forced onto the outer surface of the panel and is spreadthereon. The spread reverse umbrella-shaped cover portion exerts anadhesion force on the outer surface of the panel around the periphery ofthe through-hole. This is because an elastic force (a repulsive force)is generated due to the engagement of the attaching portion and theinner surface of the panel. That is, such an adhesion force is generatedaccording to the elastic force due to the mutual action of theumbrella-shaped attaching portion and the reverse umbrella-shaped coverportion.

Next, in the latter type of hole plug, a forward end portion of theattaching portion formed from the synthetic resin has outwardlyprojected engagement claws that are formed in the side surface (thecircumferential surface) thereof. The engagement claws are formed so asto outwardly project beyond the diameter of the through-hole. Further,because the cover portion has substantially the same construction as thecover portion of the former type of hole plug, the description thereofwill be omitted. Therefore, when the hole plug thus constructed isforced into the through-hole, the engagement claw elastically engagesthe inner surface of the panel around the periphery of the through-hole.In this case, the spread reverse umbrella-shaped cover portion exerts anadhesion force on the outer surface of the panel around the periphery ofthe through-hole due to the elastic force (the repulsive force) thereof.

A related technique is taught by Patent Document 1 described in JapaneseLaid-Open Utility Model Publication No. 61-202757. However, in theseconventional devices, when the hole plug is attached to the panel, oftentimes, the attaching portion cannot be readily inserted into thethrough-hole and reliably engage the panel. Further, in some cases, thehole plug of this type cannot provide sufficient sealing performance(waterproof property and dustproof property). Further, when the holeplug is attached, the diameter of a sealing area of the cover portionmay be excessively increased.

For example, in the former type of hole plug of the above describedconventional examples (in which the hole plug is integrally formed ofelastomer), the cover portion is formed of elastomer that has arelatively low rigidity. Therefore, when the worker inserts theumbrella-shaped portion of the attaching portion into the through-holeof the panel, the worker cannot have a crisp actual engagement feelingas to whether the umbrella-shaped portion is restored in thethrough-hole (as to whether the portion is reliably engaged to the panelinner surface). Thus, it is impossible to crisply feel as to whether theattaching portion has been completely inserted. As a result, it isnecessary to repeatedly apply an additional force to the attachingportion along the inserting direction. In some cases, it is necessary toredo the inserting operation of the attaching portion.

Also, in the case of the latter type of hole plug, the cover portion isformed from synthetic resin. Therefore, due to the rigidity of thesynthetic resin, it is possible to have the crisp actual engagementfeeling to some degree when the attaching portion is inserted into thethrough-hole. However, in this case, even if the attaching portionengages the panel inner surface, the attaching portion does not generateany elastic force (repulsive force) for bringing the umbrella-shapedcover portion into close contact with the panel outer surface. As aresult, it is necessary, for example, to provide the umbrella-shapedcover portion with a double-seal structure or to axially elongate theumbrella-shaped cover portion so that the umbrella-shaped cover portionmay exert an adhesion force (sealing performance) on the panel outersurface. However, according to the cover portion thus shaped, when theattaching portion is inserted into the through-hole, the elastic forceacting on the umbrella-shaped of cover portion (the repulsive forceagain an insertion force of the hole plug) increases due to thestructure of the cover portion. Therefore, it is difficult to insert theattaching portion into the through-hole. In addition, if theumbrella-shaped cover portion is elongated, an extent of the coverportion (the diameter of the sealing area of the cover portion) may beunnecessarily increased when the hole plug is attached to the panel.Consequently, such a hole plug cannot be used in a place where there isnot a sufficient space for the hole plug.

The present invention has been made to solve the above problems. It isone object of the present invention to provide hole plugs which can beeasily attached with an appropriate crisp actual engagement feelingwithout losing the sealing performance thereof and in which extents ofcover portions can be effectively reduced when the hole plugs are inused.

The hole plug of the present invention is constructed as follows. First,according to a first invention, a hole plug for closing a through-holeformed in a compartment wall includes an attaching portion formed from asynthetic resin, and a cover portion integrated with the attachingportion at a central portion thereof. The attaching portion can beinserted into the through-hole so as to engage one surface of thecompartment wall. The cover portion has a size and shape that canenclose the through-hole, and has a peripheral edge portion that canclosely contact the other surface of the compartment wall. The coverportion has a configuration maintaining means that is formed in theperipheral edge portion thereof or in a vicinity of the peripheral edgeportion and that can maintain a size and configuration of the peripheraledge portion when an external force is applied to the cover portion. Thecover portion has an elastic force imparting means that is formedbetween the configuration maintaining means and the central portionintegrated with the attaching portion and can undergo elastic bucklingdeformation when the external force is applied thereto. The peripheraledge portion of the cover portion is capable of closely contacting theother surface of the compartment wall by means of the elastic forceimparting means.

The configuration maintaining means may be formed such that a slidingfrictional force can be produced between the peripheral edge portion ofthe cover portion and the other side surface of the compartment wall soas to restrict the movement of the cover portion relative to thecompartment wall. Also, the configuration maintaining means may beformed by appropriately selecting the shape and the material of theperipheral edge portion or the portion in the vicinity of the peripheraledge portion such that the portion may have an increased deformationresistance against a compression force (an increased hoop stress).

According to the first embodiment of the invention, when the compressionforce is applied to the attaching portion for inserting the attachingportion into the through-hole, the peripheral edge portion of the coverportion closely contacts the other surface of the compartment wall. Atthis time, the size and configuration of the peripheral edge portion orthe portion in the vicinity of the peripheral edge portion aremaintained by means of the configuration maintaining means if anexternal force is applied to the cover portion. Thus, the portion formedwith the configuration maintaining means is securely positioned so as toclosely contact the other surface. As a result, such a portion is notexpanded by the external force. Conversely, the portion between theconfiguration maintaining means and the central portion integrated withthe attaching portion is bent inwardly with respect to the portionformed with the configuration maintaining means when the external forceis applied thereto. The bending is a result of the elastic forceimparting means while undergoing elastic buckling. Due to the elasticforce caused by this bending, the peripheral edge portion of the coverportion may closely contact the other surface of the compartment wall.

Next, according to a second embodiment of the invention, in theabove-described first invention, the cover portion is formed ofelastomer, and a portion formed with the configuration maintaining meanshas a thickness greater than a portion formed with the elastic forceimparting means.

According to the second embodiment of the invention, the cover portionis integrally formed of elastomer as a unit. Further, the portion formedwith the configuration maintaining means is thickened. Therefore, such aportion can increase the deformation resistance (an increased hoopstress), more so than a portion formed with the elastic force impartingmeans. Therefore, the external force can be easily concentrated to theportion formed with the elastic force imparting means.

Next, according to a third embodiment of the invention, in theabove-described second invention, the thickened portion formed ofelastomer and formed with the configuration maintaining means has adouble seal structure having a V-shaped cross-sectional configuration.

According to the third embodiment of the invention, the portion formedwith the configuration maintaining means of the cover portion has theV-shaped configuration in cross section. Therefore, it is possible toreliably keep a sealing posture with respect to the other surface(contact surface) of the compartment wall. Accordingly, the elasticforce can stably contact the other surface. Further, the double sealstructure may increase sealing performance of the cover portion.

The present invention may provide the following effects. First,according to the first embodiment of the invention, when the hole plugis inserted into the through-hole, the peripheral edge portion of thecover portion is not widened (i.e., is not outwardly expanded).Therefore, the diameter of a sealing area of the cover portion can bereduced. Further, as the hole plug is inserted into the through-hole,the cover portion is deformed while undergoing elastic buckling. Thus,the force required for inserting the hole plug may be reduced. Also, dueto the change in the elastic force caused by the elastic buckling, anappropriate crisp actual engagement feeling can be obtained. As aresult, the attaching operation of the hole plug can be facilitated.

Next, according to the second embodiment of the invention, the coverportion can be formed by the integral molding of elastomer. Therefore,the second invention may have increased sealing performance in additionto the effect of the first invention.

Next, according to the third embodiment of the invention, due to theelastic repulsive force generated in the cover portion, the peripheraledge portion of the cover portion may stably contact the other surfaceof the compartment wall. Therefore, the sealing performance can bestabilized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a hole plug according to a firstembodiment of the present invention.

FIG. 2 is a cross-sectional view of the hole plug, which illustrates acondition before the hole plug is inserted into a through-hole formed ina compartment panel.

FIG. 3 is a cross-sectional view of the hole plug, which illustrates acondition after the hole plug is inserted into the through-hole formedin the compartment panel.

FIG. 4 is a perspective view of a hole plug according to a secondembodiment of the present invention.

FIG. 5 is a cross-sectional view of the hole plug, which illustrates anattached condition.

FIG. 6 is an enlarged cross-sectional view of the hole plug, whichillustrates waterproof function of the hole plug.

FIG. 7 is a front view of a hole plug according to a third embodiment ofthe present invention.

FIG. 8 is a plan view of FIG. 7.

FIG. 9 is a right-hand side view of FIG. 7.

FIG. 10 is a cross-sectional view taken along line A-A of FIG. 7.

FIG. 11 is a cross-sectional view taken along line B-B of FIG. 7.

FIG. 12 is a cross-sectional view of the hole plug that is in use.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Detailed representative embodiments of the present invention aredescribed with reference to the drawings. FIGS. 1 to 3 show a hole plug10 according to a first embodiment of the present invention. FIG. 1 is aperspective view of the hole plug 10. FIG. 2 is a cross-sectional viewof the hole plug 10, which illustrates a condition before the hole plug10 is inserted into a through-hole 41 formed in a compartment wall orpanel 40. FIG. 3 is a cross-sectional view of the hole plug 10, whichillustrates a condition after the hole plug 10 is inserted into thethrough-hole 41 formed in the compartment panel 40. Further, in FIGS. 2and 3, references I and O respectively indicate inner and outer sides ofthe compartment panel 40.

It is noted that an example of the compartment panel 40 is a door panelof a vehicle. Also, the through-hole 41 corresponds to one of thethrough-holes that are formed in the compartment panel 40 at the time ofthe production thereof and the through-hole is otherwise left openwithout being used. The hole plug 10 is intended to be inserted into thethrough-hole 41 so as to seal the through-hole 41.

As best shown in FIG. 1, the hole plug 10 is composed of an attachingportion 30 formed from a synthetic resin as a bottomed cylindricalmember, and a cover portion 20 integrated with a base 30 b of theattaching portion 30 and having a truncated-umbrella-shape.

More specifically, as best shown in FIGS. 1 and 2, the bottomedcylindrically-shaped attaching portion 30 is opened at an upper orforward end 30 a. The base 30 b of the attaching portion 30 is closedand is integrated with the cover portion 20. Further, a cylindrical bodyportion 31 of the attaching portion 30 is circumferentially formed withoutwardly projecting engagement claws 32 adjacent to the forward end 30a. Further, the engagement claws 32 are formed by forming cutoutportions or slots in the cylindrical body portion 31. More specifically,the engagement claws 32 are formed so as to protrude beyond the diameterof the through-hole 41 of the compartment panel 40.

Thus, when the attaching portion 30 of the hole plug 10 is forcedthrough the through-hole 41 from the forward end 30 a (so as to beinserted thereinto toward the inner side I of the compartment panel 40),the attaching portion 30 is elastically narrowed as a result of theengagement claws 32 abutting a circumferential wall surface 42 of thethrough-hole 41 of the compartment panel 40. Then, as best shown in FIG.3, when the attaching portion 30 is further inserted so that theengagement claws 32 pass through the through-hole 41 and completelyreach the inner side I, the engagement claws 32 are elastically restoredor expanded so as to engage an inner surface 43 of the panel 40. Thus,the attaching portion 30 is coupled to the through-hole 41 so as be inan engagement condition (a locking condition) in which it is preventedfrom being detached therefrom. It is noted that the inner surface 43corresponds to one surface in the claimed invention.

Next, the cover portion 20 is formed from an elastomer which may be amaterial having a superior elasticity and sealing property. As bestshown in FIGS. 1 and 2, the cover portion 20 has a truncatedumbrella-shaped peripheral edge portion 21 that radially extends from acentral portion 22 of the cover portion 20. The cover portion 20 has asize and configuration that can enclose the through-hole 41. Further,the central portion 22 is integrally bonded to the base 30 b of theattaching portion 30.

More specifically, the peripheral edge portion 21 of the cover portion20 includes a thickened portion 21 a which has a thickness greater thanthe thickness of an umbrella-shaped side portion 23. It is noted thatthe thickened portion 21 a corresponds to a configuration maintainingmeans of the claimed invention. Because the peripheral edge portion 21of the cover portion 20 is thicker than the side portion 23, when theattaching portion 30 is inserted into the through-hole 41 (so that acompressive force, or an external force, is exerted on the cover portion20), the hoop stress acting on the peripheral edge portion 21 (thickenedportion 21 a) is increased. Therefore, even if the cover portion 20 isapplied with the external force, the configuration of the peripheraledge portion 21 is maintained.

Further, the thickened portion 21 a of the peripheral edge portion 21 isformed with a seal portion 21 b having a V-shaped cross-sectionalconfiguration. More specifically, as best shown in FIGS. 2 and 3, whenthe external force is applied in order to insert the attaching portion30 into the through-hole 41, the seal portion 21 b comes into contactwith an outer surface 44 of the compartment panel 40, thereby exertingan adhesion force thereto. More specifically, the V-shaped contactportion generates a sustaining force so as to keep a desired sealingposture of the cover portion 20 when the external force is exertedthereto. Further, a double-sealing structure is formed so that thesealing performance can be increased. This is because the contactportion of the seal portion 21 b has a V-shaped cross section so thatthe sealing performance can be effectively performed. It is noted thatthe outer side surface 44 corresponds to the other surface in theclaimed invention.

Conversely, the side portion 23 of the cover portion 20 is formed with athinned portion 23 a that has a thickness thinner than the thickness ofthe peripheral edge portion 21. In other words, when the above-mentionedexternal force is exerted on the cover portion 20, the thinned portion23 a can more easily deform than the thickened portion 21 a of theperipheral edge portion 21. Therefore, this external force isconcentrated on the side portion 23 rather than the peripheral edgeportion 21 such that the side portion 23 can be greatly deformed. It isnoted that the thinned portion 23 a corresponds to an elastic forceimparting means in the claimed invention.

Next, a function of the attaching portion 30 and the cover portion 20during an attaching operation of the hole plug 10 will be specificallydescribed with reference to FIGS. 2 and 3.

First, as best shown in FIG. 2, when an external force in order toinsert the attaching portion 30 into the through-hole 41 is applied, theperipheral edge portion 21 of the cover portion 20 closely contacts theouter side surface 44 of the compartment panel 40. More specifically,the seal portion 21 b formed in the peripheral edge portion 21 andhaving a V-shaped cross section closely contacts the outer side surface44, thereby forming a double seal. At this time, if the external forceis further applied to the cover portion 20, the size and configurationof the peripheral edge portion 21 can be maintained due to the thickenedportion 21 a. Therefore, the peripheral edge portion 21 can be securelyseated or positioned at the location where the peripheral edge portion21 originally contacts the outer surface 44 of the compartment panel 40.Thus, the cover portion 20 can be prevented from expanding along theouter surface 44.

Consequently, this external force is concentrated on the side portion 23of the cover portion 20. More specifically, as best shown in FIG. 3, theside portion 23 is thinner and longer than the peripheral edge portion21. Therefore, when the external force is applied to the positionedperipheral edge portion 21 from an offset position, the side portion 23receives a large bending force. As a result, the side portion 23 is bentinwardly while undergoing local elastic buckling. Thus, due to thiselastic buckling, the force required for inserting the hole plug 10 isreduced.

Further, at this time, the side portion 23 is applied with an elasticforce (a restoring force) corresponding to the elastic deformation dueto the bending thereof. This elastic force acts such that the peripheraledge portion 21 of the cover portion 20 is brought into close contactwith the outer side surface 44 of the compartment panel 40. Further, dueto this elastic force, the seal portion 21 b, having a V-shapedcross-sectional configuration and formed on the cover portion 20,provides a resisting force against a force that causes the peripheraledge portion 21 to move along the outer surface 44.

Then, when the engagement claw 32 passes through the through-hole 41 andis elastically expanded the attaching portion 30 engages the innersurface 43 so as to exert an engagement force that acts against theabove-mentioned elastic force. Thus, the peripheral edge portion 21 ofthe cover portion 20 is held in a condition in which it closely contactsthe outer surface 44 of the compartment panel 40.

Subsequently, a method of using the hole plug 10 of this embodiment willbe described with reference to FIGS. 2 and 3. First, the attachingportion 30 of the hole plug 10 is forced into the through-hole 41 fromthe forward end 30 a so as to be inserted toward the inner side I. As aresult, as best shown in FIG. 2, the peripheral edge portion 21 of thecover portion 20 is brought into close contact with the outer surface 44of the compartment panel 40. Thereafter, when the attaching portion 30is further pressed toward the inner side I, the peripheral edge portion21 of the cover portion 20 is securely positioned on the outer surface44 without being expanded along the outer surface 44, and the sideportion 23 is bent inwardly while undergoing elastic buckling. That is,the elastic force (the repulsive force) acting on the cover portion 20is reduced. At this time, a worker attaching the hole plug 10 can feelthis change in the elastic force (the repulsive force) as a desiredcrisp actual engagement feeling. Therefore, when the attaching portion30 is inserted until it engages the inner surface 43 of the compartmentpanel 40, the hole plug 10 is fitted into the through-hole 41 so thatthe inner side I is brought into a sealing condition.

When the hole plug 10 of this embodiment is inserted into thethrough-hole 41, the peripheral edge portion 21 of the cover portion 20is maintained at a desired position, so that the diameter of a sealingarea of the cover portion 20 can be reduced. Further, as the hole plug10 is inserted into the through-hole 41, the cover portion 20 isdeformed while undergoing elastic buckling. Therefore, the forcerequired for inserting the hole plug 10 may be reduced. Also, due to thechange in the elastic force caused by the elastic buckling, anappropriate or actual crisp feeling of engagement can be obtained. As aresult, the attaching operation of the hole plug 10 can be facilitated.

Further, the cover portion 20 is integrally formed from the elastomerand has a thickened peripheral edge portion 21 and a thinned sideportion 23. The above-mentioned effect can be obtained by simpleconstruction described above. Moreover, due to the seal portion 21 bbeing formed in the cover portion 20 and having a V-shapedcross-sectional configuration, the adhesion contact force can be stablyexerted on the outer surface 44 of the compartment panel 40. As aresult, sealing performance can be stably generated.

A second detailed representative embodiment of the present invention isdescribed with reference to FIGS. 4 and 5. FIG. 4 is a perspective viewof a hole plug 110. FIG. 5 is a cross-sectional view of the hole plug110, which illustrates a condition after the hole plug 110 is attached.

As shown in FIGS. 4 and 5, the body member 130 is formed as aplate-shaped member. In this embodiment, the hole 132 is formed as around hole. An example of the body member 130 is an outer plate of anautomobile. Further, the hole 132 formed in this outer plate is one ofthe holes that is intended for use as flow holes for coating materialduring coating operations and as operation holes for mountingcomponents. Such a hole 132 is required when the automobile ismanufactured. However, once the manufacturing operation of theautomobile is completed, the hole 132 provides no further function atall and thus is unnecessary. Generally, the hole 132 is closed after itbecomes unnecessary. The hole plug 110 is intended to be inserted intothe hole 132 so as to close the hole 132. The hole plug 110 may have awaterproof function in order to intercept the passage of water betweeninterior and exterior sides of the body member 130.

The hole plug 110 is composed of a fitting portion 120 and a blockingportion 125. As seen in FIG. 5, the blocking portion 125 is attached toan upper end of the fitting portion 120. The fitting portion 120 and theblocking portion 125 are formed as an integral unit by the molding of arigid synthetic resin. The fitting portion 120 is a cylindrical portionthat is fitted into the hole 132 formed in the body member 130. As seenin the drawing, a desired number (e.g., four in this example) ofengagement claws 121 are formed at the lower end of the fitting portion120. In this embodiment, the four engagement claws 121 arecircumferentially positioned at 90 degree intervals. However, any numberof engagement claws may be formed so as to be circumferentiallypositioned over the entire periphery of the fitting portion 120, ifnecessary.

As shown in FIG. 4, the engagement claws 121 are formed by formingcutout portions or slots 126 in the fitting portion 120. Therefore, theengagement claws 121 can be independently radially flexed. Morespecifically, the engagement claws 121 are radially outwardly biased.Therefore, the engagement claws 121 engage the lower edge of the hole132 of the body member 130, thereby preventing upward detachment of thefitting portion 120, as seen in FIG. 5.

The blocking portion 125 is the portion for blocking the hole 132 formedin the body member 130 and is formed as a disc-shaped member having anarea larger than that of the hole 132. As shown in the drawing, thelower surface of the blocking portion 125 is formed with a centralprotrusion 140 and a circumferential seal member 111. Also, the upperend of the fitting portion 120 is integrally attached to the lowersurface of the blocking portion 125 at a middle portion between theprotrusion 140 and the seal member 111. The protrusion 140 is inherentlyformed when the blocking portion 125 is formed by the resin molding. Thelength of the protrusion 140 is smaller than that of the fitting portion120.

The seal member 111 is composed of two annular seal strips 111 a and 111b that are continuously formed. The seal strip 111 a iscircumferentially outwardly positioned, and the seal strip 111 b iscircumferentially inwardly positioned. The seal strips 111 a and 111 bare integrated at their base portions and are securely attached to theblock portion 125 by an appropriate fixing means such as adhesion.

The outwardly positioned seal strip 111 a is arranged so as to beradially outwardly directed and to be downwardly inclined toward thebody member 130, and is positioned so as to have an appropriate pressingcontact with the surface of the body member 130. To the contrary, theinwardly positioned seal strip 111 b is arranged so as to be radiallyinwardly directed and to be downwardly inclined toward the body member130, and is positioned so as to have an appropriate pressing contactwith the surface of the body member 130. That is, the seal strips 111 aand 111 b are arranged so as to be radially oppositely directed.

The seal strips 111 a and 111 b constituting the seal member 111 areformed of a material that can provide a sealing function. For example,they may be formed of a rubber material or a resin material such as anelastomer.

Next, the sealing function of the hole plug 110 of this embodimentconstructed as described above will be described with reference to FIG.6. FIG. 6 is an enlarged view of the left-hand side of FIG. 5, whichillustrates a cross-sectional view of the hole plug 110.

First, with regard to water that enters from the outer side of the bodymember 130 toward the inner side (i.e., from the upper side toward thelower side as seen in the drawing). For water that enters in a directionindicated shown by the arrows (a) a sealing function and waterprooffunction can be performed by means of the outwardly positioned sealstrip 111 a of the seal member 111. That is, when the water enters inthe direction shown by the arrows (a), the water pressure of the watermay act on the outer surface of the seal strip 111 a so that thepressing contact force between the seal strip 1 a and the body member130 can be increased. As a result, the water entering in the directionshown by the arrows (a) can be prevented by the seal strip 111 a so thatthe hole plug 110 may provide a sufficient waterproof function.

Next, with regard to water that enters from the inner side of the bodymember 130 toward the outer side (i.e., from the lower side toward theupper side as seen in the drawing). For water that enters in a reversedirection indicated shown by the arrows (b) a sealing function andwaterproof function can be performed by means of the inwardly positionedseal strip 111 b of the seal member 111. That is, when the water entersin the direction shown by the arrows (b), the water pressure of thewater may act on the outer surface of the seal strip 111 b so that thepressing contact force between the seal strip 111 b and the body member130 can be increased. As a result, the water entering in the directionshown by the arrows (b) can also be prevented by the seal strip 111 b sothat the hole plug 110 may provide a sufficient waterproof function.

That is, according to the hole plug 110 of this embodiment, a waterprooffunction is provided with respect to water that enters in bothdirections indicated by the arrows (a) and (b), i.e., water that entersfrom each of the inner and outer sides of the body member 130.

In this embodiment, as in the prior art, the engagement claws 121 of thefitting portion 120 unremovably engage the hole 132. Therefore, apressing contact force is generated between the seal strips 111 a and111 b and the surface of the body member 130, thereby producing asealing function. As a result, more specifically, the waterprooffunction of the seal member 111 is a combination of these two sealfunctions.

In this way, according to the hole plug 110 of this embodiment, which isattached by fitting the hole plug 110 into the hole 132 formed in thebody member 130, the seal member 111 can prevent water from enteringthrough the hole 132 from both of the outer and inner sides of the bodymember 130. Therefore, the seal member 111 can effectively provide atwo-way waterproofing function.

Further, the seal member is composed of the two seal members. One of theseal strips can prevent water from entering from one side to the otherside of the body member 130. Conversely, the other of the seal stripscan reliably prevent water from entering from the other side to one sideof the body member 130. As a result, the two seal members caneffectively provide a waterproof function that can prevent water fromentering from both sides.

Further, when the hole plug 110 is attached to the body member 130, itis possible to prevent water intrusion regardless of whether the holeplug is attached from the exterior or the interior of the vehicle.Therefore, there is no need to observe the attaching direction of thehole plug 110. As a result, workability for attaching the hole plug canbe increased.

A third detailed representative embodiment of the present invention isdescribed with reference to the drawings. FIG. 7 is a front view of ahole plug. FIG. 8 is a plan view of FIG. 7. FIG. 9 is a right-hand sideview of FIG. 7. FIG. 10 is a cross-sectional view taken along line A-Aof FIG. 7. FIG. 11 is a cross-sectional view taken along line B-B ofFIG. 7.

As will be apparent from these drawings, the hole plug is composed of aseal portion 210 and a fitting portion 220. The seal portion 210 has acircular disc-shaped configuration. The fitting portion 220 has acylindrical configuration that corresponds to the configuration of athrough-hole 232 formed in a body member 230 described below.

The seal member 210 is formed by covering a core member 212 with acovering material 214. The core member 212 is formed from a rigidsynthetic resin such as polypropylene (PP). Conversely, the coveringmaterial 214 is formed from a flexible synthetic resin such as elastomerresin. That is, the seal portion 210 has a structure in which the entiresurface of the rigid core member 212 is covered with a thin flexiblecovering material 214 (FIGS. 10 and 11). It should be noted that an edgeportion 216, i.e., an outer peripheral edge of the seal portion 210, isformed from only the flexible covering material 214.

The fitting portion 220 is integrally formed with the core member 212.Therefore, the fitting portion 220 is also formed from the rigidsynthetic resin. The outer side portion of the fitting portion 220 isintegrally formed with engagement claws 222 and 226 that arerespectively positioned at four positions, i.e., two positions on theright and left and two positions on the front and rear in FIG. 7. Aswill be apparent from FIGS. 8 and 10, the right and left engagementclaws 222 in FIG. 7 protrude outwardly with a curvature from the endportion of the fitting portion 220. Thus, the engagement claws 222 havea desired flexibility. The engagement claws 222 are respectively formedwith outwardly projecting engagement portions 223. The engagementportions 223 are positioned near the forward ends of the engagementclaws 222 and further protrude outwardly therefrom. Conversely, as willbe apparent from FIG. 11, the front and rear engagement claws 26 in FIG.7 are connected to the fitting portion 220 at the end portions thereof.In other words, the engagement claws 226 are formed by forming cutoutportions or slots in the fitting portion 220. Therefore, the engagementclaws 226 have a desired flexibility. The engagement claws 226 are alsorespectively formed with outwardly projecting engagement portions 227.

FIG. 12 is a cross-sectional view of the hole plug that is in use. Inthis drawing, the through-hole 232 corresponds to one of thethrough-holes that are formed in the body member 230 (e.g., a vehiclebody) thereof and is otherwise left open without being used. The holeplug is intended to be inserted into the through-hole 232 forwaterproofing and dustproofing.

In order to seal the through-hole 232, the fitting portion 220 of thehole plug is inserted into the through-hole 232 from the outer surfaceside of the body member 230. As a result, the engagement claws 222 and226 pass through the through-hole 232 while being flexed inwardly sothat the respective engagement portions 223 and 227 engage theperipheral edge of the through-hole 232 on the inner surface of the bodymember 230.

The dimension of the fitting portion 220 has a size that permits it toeasily fit into the through-hole 232. Also, the engagement claws 222 and226 can easily and independently flex. Therefore, the fitting portion220 can be inserted into the through-hole 232 with a small force.Further, since the engagement claws 222 and 226 are formed from a rigidsynthetic resin, when the engagement portions 223 and 227 engage theinner surface of the body member 230 as described above, an actual crispfeeling of engagement can be obtained. In addition, the hole plug can bereliably attached to the body member 230 with a sufficient retainingforce.

Although, the right and left engagement claws 222 and the front and rearengagement claws 226 in FIG. 7 are different from each other, such adifference in shape is not essential in function. Therefore, it isnaturally possible to unify the shape of the engagement claws 222 and226 to either of the individual shapes.

In a condition in which the fitting portion 220 has been thus fittedinto the through-hole 232, the seal portion 210 of the hole plug isbeing pressed against the outer surface of the body member 230 aroundthe through-hole 232. In particular, because the edge portion 216 of theseal portion 210 is formed from only the soft covering material 214, theedge portion 216 has good adhesion with the outer surface of the bodymember 230. Therefore, the hole plug may have good waterproof anddustproof performances. Further, although the edge portion 216 is formedfrom only the covering material 214, it is possible to form the edgeportion 216 from the core member 212 and the covering material 214, andto design the hole plug such that the covering material 214 of the edgeportion 216 has a thickness greater than the covering material 214 ofthe main portion.

As shown in FIGS. 10 and 11, the covering material 214 is only providedto the portion in which waterproof or dustproof function is required.The hole plug of this embodiment is, for example, formed by filling amolding die with a flexible synthetic resin (the covering material 214),and then filling the molding die with a rigid synthetic resin (the corematerial 212). In this forming method, it may be impossible to definethe boundary between the portion of the core member 212 that is coveredwith the covering material 214 and the portion thereof that is notcovered with the covering material 214. However, this boundary is not avery important factor. What is important is that the core member 212 iscovered by the covering material 214 at least in the seal portion 210.Further, the fitting portion 220 and the engagement claws 222 and 226may optionally be covered with the covering material 214.

Various changes and modifications may be made to the three embodimentsdescribed above. Initially, in the first embodiment, the thickenedportion 21 a is formed at the peripheral edge portion 21 of the coverportion 20. However, the thickened portion can be formed in the vicinityof the peripheral edge portion in consideration of particular designproperties. In this case also, it is possible to maintain the size andconfiguration of the peripheral edge portion.

Further, the side portion 23 of the cover portion 20 is formed with thethinned portion 23 a as the elastic force imparting means. However,instead, the side portion of the cover portion may be partially formedwith cutout portions so that concentration of the external force (stressconcentration) can occur. In addition, it is possible to change theoffset position of the thickened portion that is applied with theexternal force so that a large bending stress is exerted on the sideportion.

Further, in the first embodiment, the through-hole 41 has a circularshape, and the hole plug 10 is shaped so as to correspond to the shapeof the through-hole. However, the through-hole may have a rectangular ortriangular shape. Naturally, in such a case, the shape of the attachingportion and the cover portion is modified so as to correspond to theshape of the through-hole.

Moreover, in the second embodiment, the hole 132 formed in the bodymember 130 has a circular shape. However, the hole 132 may have arectangular shape. Similarly, the seal members 111 a and 111 b of theseal member 111 have a circular shape. Naturally, the seal members 111 aand 111 b can be modified so as to correspond to the shape of the hole132. Further, it should be noted that the seal members must becontinuously formed regardless of the shape thereof.

1. A hole plug for closing a through-hole formed in a compartment wall,comprising: an attaching portion formed from a synthetic resin, theattaching portion can be inserted into the through-hole so as to engageone surface of the compartment wall; and a cover portion integrated withthe attaching portion at a central portion thereof, the cover portionhaving a size and shape that can enclose the through-hole and having aperipheral edge portion that can closely contact the other surface ofthe compartment wall, wherein the cover portion has a configurationmaintaining means that is formed in the peripheral edge portion thereofor in a vicinity of the peripheral edge portion and that can maintain asize and configuration of the peripheral edge portion when an externalforce is applied to the cover portion, and wherein the cover portion hasan elastic force imparting means that is formed between theconfiguration maintaining means and the central portion integrated withthe attaching portion and that can undergo elastic buckling deformationwhen the external force is applied thereto, the peripheral edge portionof the cover portion being capable to closely contact the other surfaceof the compartment wall by means of the elastic force imparting means.2. The hole plug according to claim 1, wherein the cover portion isformed of elastomer, and wherein a portion formed with the configurationmaintaining means has a thickness greater than a portion formed with theelastic force imparting means.
 3. A hole plug according to claim 2,wherein the thickened portion formed of elastomer and formed with theconfiguration maintaining means has a double seal structure having aV-shaped cross-sectional configuration.